1. Field of the Invention
The present invention relates to a structural body and a method of producing the same having an excellent heat cycle resistivity.
2. Description of Related Art
Generally, an electrostatic chuck is used for chucking a semiconductor wafer and retaining it in the steps of film forming such as transfer, exposure, thermal CVD (Chemical Vapor Deposition method), plasma CVD, and sputtering of the semiconductor wafer, fine working, washing, etching, dicing and so on. As a substrate of the electrostatic chuck mentioned above, and as a substrate of the heater, dense ceramics having a high density are used recently. Especially in an apparatus for producing semiconductors, halogen corrosive gasses such as CIF3 and so on are widely used as etching gas and cleaning gas. Moreover, in order to heat and cool the semiconductor wafer rapidly while it is retained, it is desired that the substrate of the electrostatic chuck has a high heat conductivity. Further, it is desired that the substrate of the electrostatic chuck has a thermal shock resistivity so as to be fractured due to a rapid temperature variation.
Dense aluminum nitride has a high corrosive resistivity with respect to the halogen corrosive gas as mentioned above. Moreover, the dense aluminum nitride is known as a material having a high heat conductivity such as a volume resistivity of greater than 108 ohm-cm. In addition, the dense aluminum nitride is known as a substance having a high thermal shock resistivity. Therefore, it is thought to be preferred that the substrate of the electrostatic chuck or the heater used for producing semiconductors is formed by an aluminum nitride sintered body.
As a member having corrosive resistivity exposed to a corrosive gas in the apparatus for producing semiconductors mentioned above, the inventors studied a corrosion resistive member in which a silicon carbide film was formed on a surface of the aluminum nitride substrate by means of chemical vapor deposition method. When such a corrosion resistive member was subjected to a heat cycle was applied to the corrosion resistive member. In this case, it was found that cracks or abruptions were liable to be generated according to an increase of heat cycle numbers. If cracks were generated in the corrosion resistive member, AIN substrate was eroded by the corrosive gas, so that the silicon carbide film was peeled off.
An object of the present invention is to provide a structural body in which a silicon carbide film is formed on an aluminum nitride sintered body, which does not generate cracks or abruptions of the silicon carbide film when a heat cycle is applied to the structural body.
According to the invention, a structural body comprises an aluminum nitride sintered body, a silicon carbide film formed on a surface of said aluminum nitride sintered body, and an intermediate layer generated between said aluminum nitride sintered body and said silicon carbide film, said intermediate layer being mainly made of silicon nitride.
Moreover, according to the invention, a method of producing the structural body mentioned above, comprises the steps of flowing hydrogen at a film forming temperature; flowing a gas for a first silicon generation compound including at least silicon, chlorine and hydrogen; and flowing a gas for a second silicon generation compound and a carbon generation compound; thereby forming said silicon carbide film to said aluminum nitride sintered body by means of a chemical vapor deposition method.